The present invention relates to a signaling control technique for controlling a signaling process in a communications network system comprised of a managing network, a control network, and a user data transmission network operating independently from one another.
In recent years, to implement various types of IP-based multimedia services, techniques for controlling and managing a large-capacity IP (Internet protocol) photonics network have been attracting a great deal of attention. In the large-capacity IP network, WDM (wavelength division multiplexed), SONET (synchronous optical network)/SDH (synchronous digital hierarchy), and IP/MPLS (multiprotocol label switching) networks are integrated into a single system.
Conventionally, transmission-type core networks, typically represented by WDM and SONET/SDH techniques, are constructed as centralized management systems, through which services have been provided with high reliability. On the other hand, packet switching networks, typically represented by an IP/MPLS technique, are constructed as autonomously distributed flexible control system, which have high scalability. To make use of the advantages of both types of networks, while reducing the network operation cost, it becomes important to realize an intermediate system positioned across the centralized management and the autonomously distributed control.
To this end, various studies have been made, on the basis of the signaling techniques of OIF-UNI (optical interworking forum-user network interface) and GMPLS (generalized multiprotocol label switching). Such studies include, for example, setting a layer path or changing the frequency band on demand, and carrying out short-cut control of optical paths.
The outline of the GMPLS, which is the prerequisite technique of the present invention, will be explained below. GMPLS is a technique that expands the MPLS technique standardized in the IP network so as to be applicable to other fields, such as TDM layers and optical layers, in order to integrate the topologies of SONET and WDM or to set paths in a dynamic manner.
The goal of the GMPLS is to prevent network management cost from increasing even if the network scale expands, by allowing each node to autonomously manage the network topology, in place of centralized management of detailed network topology at the network management system (NMS).
Instead of issuing instructions from the network management system (NMS) to change the configuration of the respective communication nodes, the end node of a path is requested to set a new path. This arrangement can reduce time required to set up a network in response to a user's request.
The GMPLS also aims at improving the efficiency of network control, as well as realizing interoperability with other vender apparatuses. This is achieved by expanding the control network of the MPLS standardized in the IP network so as to be applicable to carrier networks in common, instead of producing an independent control form for each of the carrier networks (of core communication providers).
FIG. 1 illustrates an example of a proposed communications network system, which includes a management plane (i.e., a management network) 10, a control plane (i.e., a control network) 20, and a data plane 30 (which is a user data transmission network).
The management plane 10 implements management of apparatuses, networks, and services, and regulates the interface with the user (or the network operator).
The control plane 20 is comprised of control nodes 21, 22, and 23, between which routing information is transmitted to establish the optimum path to the destination. Each of the control nodes 21, 22, and 23 corresponds to one of the communication nodes 31, 32 and 33 placed on the data plane 30.
The data plane 30 is comprised of the communication nodes 31, 32, and 33, each of which switches data traffic according to the instruction from the associated control node (i.e., one of the control nodes 21, 22, and 23) to transmit user data to the destination efficiently.
Each pair of the control node and the communication node constitutes a signaling-based communication apparatus. Namely, the control node 21 and the communication node 31 comprise a signaling-based communication apparatus. The same applies to the pair of control node 22 and communication node 32, and the pair of control node 23 and communication node 33.
In this communications network, the configuration of each communication apparatus can be varied under the signaling control, and the communication apparatuses are mutually connected via the control plane 20. All the communication nodes 31-33 are connected to the management plane 10 via the control plane 20 to receive an instruction for changing the configuration from the management plane 10. The topology and the protocol of the management plane 10 generally differ from those of the control plane 20.
However, in reality, it is difficult to replace all the non-signaling-based communications apparatuses at once with signaling-based communication apparatuses in order to introduce the above-described signaling control technique in the communications network. This is mainly because of economic reasons and practical reasons pertaining to time-consuming construction. If non-signaling-based communication apparatuses remain as a part of the communications network, signaling messages can not reach the communication nodes of such non-signaling-based communication apparatuses because these communication nodes are not connected to the control plane 20 due to not having associated control nodes.
On the other hand, in the conventional signaling-control-based network, such as the IP network, the control message transmission network and the user data transmission network are the same, and therefore, all the communication nodes are connected under the same protocol. However, if the network conditions of the prerequisite networks greatly differ from each other, and if the control plane 20 and the data plane 30 are constructed independently from each other, then it is difficult for the topology information collecting protocol of the control plane 20 to grasp the existence of non-signaling-based communication apparatuses. This results in a contradiction between the collected topology information and the requested path setting information. In other words, it is not possible for the conventional IP network to adjust the configuration for the purpose of setting a new path, using only data transmission on the control plane 20.